Engineering Commons^™

Electrochemical And Surface Compositional Studies On Uranium Dioxide, Mayuri Razdan

Electronic Thesis and Dissertation Repository

This thesis describes electrochemical and surface compositional studies performed on a number of simulated nuclear fuel (SIMFUEL) materials under conditions relevant to permanent disposal of spent nuclear fuel in a geologic repository. This is important since a number of critical issues have been identified in the event of waste container failure. The research performed was mainly focused in three areas: (i) the influence of low pH on the surface chemistry of UO₂, since acidity could develop within corrosion product deposits and flaws in the fuel; (ii) the combined influence of dissolved H₂ and H₂O_{2 …}

Assessing Different Zeolitic Adsorbents For Their Potential Use In Kr And Xe Separation, Breetha Alagappan

UNLV Theses, Dissertations, Professional Papers, and Capstones

Separation of Kr from Xe is an important problem in spent nuclear fuel fission gas management. The energy intensive and expensive cryogenic distillation method is currently used to separate these gases. In this thesis, we have carried out the research into appropriate sorbents for the separation of Kr and Xe using pressure swing adsorption. We have examined zeolites using gas adsorption studies as they have the potential to be more cost effective than other sorbents. Zeolites are microporous aluminosilicates and have ordered pore structures. The pores in zeolites have extra-framework cations are substantially free to move. The mobility of cations …

Characterization Techniques And Electrolyte Separator Performance Investigation For All Vanadium Redox Flow Battery, Zhijiang Tang

Doctoral Dissertations

The all-vanadium redox flow battery (VRFB) is an excellent prospect for large scale energy storage in an electricity grid level application. High battery performance has lately been achieved by using a novel cell configuration with advanced materials. However, more work is still required to better understand the reaction kinetics and transport behaviors in the battery to guide battery system optimization and new battery material development. The first part of my work is the characterization of the battery systems with flow-through or flow-by cell configurations. The configuration difference between two cell structures exhibit significantly different polarization behavior. The battery output can …

Tin Sensitization For Electroless Plating, Xingfei Wei

Graduate Theses and Dissertations

The tin sensitization process has been used in electroless plating since 1940s Brenner and Riddell developed the electroless plating for surface metallization method. It was found to be an interesting topic to study tin sensitization for chemically controlling metal deposition on different substrates, because the tin sensitization process had critical effects on the electroless plated metal thin films. Nowadays electroless plating metal deposition is still an important method for depositing metals. It has a few advantages over the vapor deposition and electrodeposition method, such as work in an ambient condition, on nonconductive substrates, and without extra power input. Applying electroless …

Microfluidics Guided By Redox-Magnetohydrodynamics (Mhd) For Lab-On-A-Chip Applications, Vishal Sahore

Graduate Theses and Dissertations

Unique microfluidic control actuated by simply turning off and on microfabricated electrodes in a small-volume system was investigated for lab-on-a-chip applications. This was accomplished using a relatively new pumping technique of redox-magnetohydrodynamics (MHD), which as shown in this dissertation generated the important microfluidic features of flat flow profile and fluid circulation. MHD is driven by the body force, FB = j × B, which is the magnetic part of the Lorentz force equation, and its direction is given by the right hand rule. The ionic current density, j, was generated in an equimolar solution of potassium ferri/ferro cyanide by applying …

Monodentate, Bidentate And Photocrosslinkable Thiol Ligands For Improving Aqueous Biocompatible Quantum Dots, Hiroko Takeuchi

Graduate Theses and Dissertations

Water-soluble Quantum Dots (QDs) are highly sensitive fluorescent probes that are often used to study biological species. One of the most common ways to render QDs water-soluble for such applications is to apply hydrophilic thiolated ligands to the QD surface. However, these ligands are labile and can be easily exchanged on the QD surface, which can severely limit their application. As one way to overcome this limitation while maintaining a small colloidal size of QDs, we developed a method to stabilize hydrophilic thiolated ligands on the surface of QDs through the formation of a crosslinked shell using a photocrosslinking approach. …

Synthesis Of Ferrocene Copolymers And Investigation Of Their Electrochemical Properties., Alzharani Ahmed

Electronic Theses & Dissertations

Ferrocene is an organometallic compound. It is a classical metallocene consisting of two cyclopentadienyl rings bound on opposite sides of a central iron atom. Such organometallic compounds are also called sandwich compounds. Ferrocene copolymers have well known electrochemical capabilities. The main objective of this thesis is to synthesize vinyl ferrocene copolymers and test their electrochemical properties in aqueous solutions with different electrolytes (sodium nitrate, sodium perchlorate, and phosphate buffered saline). Vinylferrocene and 3-phenyl[5]ferrocenophane-1,5- dimethylene were synthesized using a Wittig reaction. Both ferrocene monomers were copolymerized with N-ethylmaleimide and N-phenylmaleimide and the resulting polymers were analyzed by Gel Permeation chromatography, IR …

Structural Characterization Of Super-Acid Oligomerized Fatty Esters., Esam Allehyani

Electronic Theses & Dissertations

Fatty acid methyl esters can be oligomerized with very strong acid catalysts - superacids such as tetrafluoroboric or triflic acid with formation of dimer and trimer fatty acids at much lower temperature, such as 80-90 °C, than what is used presently. Insight into the reaction of polymerization of fatty esters/ acids can be obtained by structural characterization. This would determine the properties of the oligomeric products and their ability to substitute currently used materials. It was presumed that dimer fatty, trimer fatty acid esters, and oligomeric fatty acid esters are produced by polymerization of fatty acid methyl esters by a …

Applying Computational Methods To Interpret Experimental Results In Tribology And Enantioselective Catalysis, Michael Garvey

Theses and Dissertations

Computational methods are rapidly becoming a mainstay in the field of chemistry. Advances in computational methods (both theory and implementation), increasing availability of computational resources and the advancement of parallel computing are some of the major forces driving this trend.

It is now possible to perform density functional theory (DFT) calculations with chemical accuracy for model systems that can be interrogated experimentally. This allows computational methods to supplement or complement experimental methods. There are even cases where DFT calculations can give insight into processes and interactions that cannot be interrogated directly by current experimental methods.

This work presents several examples …

An Experimental Investigation Characterizing The Tribological Performance Of Natural And Synthetic Biolubricants Composed Of Carboxylic Acids For Energy Conservation And Sustainability, Carlton Jonathan Reeves

Theses and Dissertations

Over the last several decades the lubrication industry has been striving to bring bio-based lubricants known as biolubricants to prominence. The reasons for the increased environmental initiatives are due to depletion of oil reserves, increases in oil price, stringent government regulations on petroleum-based oils, and most importantly, concerns for protecting the environment. With an estimated, 50% of all lubricants entering the environment and much of these being composed of toxic mineral oils, biolubricants have begun to witness a resurgence. This experimental investigation seeks to develop a new class of ecofriendly biolubricants that are less toxic to the environment, derived from …

Lipid Production By Microalgae Treating Municipal Wastewater, James Edward Kelley

Master's Theses

Microalgae hold much promise as a feedstock in liquid biofuel production. Lipid content of microalgae cells range from 30-80% dry weight of biomass. It is projected that microalgae can produce between 1,000-6,500 gallons/acre/year of oil. Currently, production of industrial algae operates in open raceway ponds that use minimal capital and energy inputs to culture algae. Raceway ponds can also be used to grow microalgae from municipal waste streams. Although high biomass productivity can be achieved in these systems, there remains a large production gap between large volumes of biomass cultivation and high lipid content from microalgae cells. Low lipid content …

Formulation Development Of A Polymer-Drug Matrix With A Controlled Release Profile For The Treatment Of Glaucoma, Eric W. Tsoi

Master's Theses

Glaucoma is the leading cause of blindness in the United States accounting for 9-12% of all cases of blindness. Currently, the front line treatment for glaucoma are prostaglandins that may have to be taken up to several times a day. Even with proper treatment, roughly 11% of the patients using the treatment are non-compliant and lose their vision. In this project, ForSight Laboratories has developed a pharmaceutical drug delivering implant with the capability of sustaining long-term release of a prostaglandin as a new way to treat the condition. This project reports the product development of a polymer drug matrix with …

Spectroscopic And Kinetic Study Of Copper-Exchanged Zeolites For The Selective Catalytic Reduction Of Nox With Ammonia, Shane Adam Bates

Open Access Dissertations

The recent application of metal-exchanged, small-pore zeolites for use in the selective catalytic reduction (SCR) of NO_x with ammonia NH₃ for automotive deNO_x applications has been a great stride in achieving emission standard goals. Copper-exchanged SSZ-13 (Cu-SSZ-13), the small-pore zeolite in this study, has been shown to be very hydrothermally stable and active under conditions presented in the exhaust of the lean-burn diesel engine. In this work, detailed studies were performed to identify many aspects of the active site(s) in Cu-SSZ-13 in order to learn about the standard SCR mechanism.

A series of seven Cu-SSZ-13 samples were …

The Effect Of Composition On The Linear And Nonlinear Mechanical Properties Of Particulate Filled Elastomers, Oluwaseyi Ogebule

Open Access Dissertations

Engineering elastomers are materials capable of undergoing large deformation upon load application and recovering upon load removal. From car tires to building vibration isolator systems, elastomers are the most versatile of engineering materials. The inclusion of particulate fillers into elastomers enhances their mechanical properties (modulus, tensile strength, toughness, tear resistance, etc) thereby extending their applicability to more demanding functions. The automotive, healthcare, construction, adhesives and consumer products are some of the many industries that produce finished goods containing elastomeric parts.

Despite the various concepts on reinforcement in filled elastomers, a complete understanding of their linear viscoelastic properties and the nonlinear …

Elucidation Of Chiral Recognition Mechanisms Of Solutes By Amylose Tris[(S)-Alpha-Methylbenzylcarbamate] Sorbent, Hung-Wei Tsui

Open Access Dissertations

Enantioselective separations of chiral molecules are important in various chemical fields, such as pharmaceuticals and agrochemicals industries. Polysaccharide-based sorbents have been widely used in chiral liquid chromatography. The recognition mechanisms which determine their enantioselectivities are not completely understood.

In this dissertation, the chiral recognition mechanisms of a widely used commercial sorbent, amylose tris[(S)-alpha-methylbenzylcarbamate], for benzoin (B) enantiomers were first studied. The HPLC data for benzoin with pure n-hexane as the mobile phase have been obtained. The behavior of sorbent-solute-hexane systems can be interpreted by considering only sorbent solute two-component interactions. Infrared (IR) spectra showed evidence of substantial hydrogen bonding (H-bonding) …

Development Of Quantitative Ft- Ir Methods For Analyzing The Cure Kinetics Of Epoxy Resins, Sang Ha Son

Open Access Dissertations

Epoxy thermosets are important engineering materials with applications in coating, adhesives, packaging and as structural components in a variety of advanced engineering products. The ultimate performance of polymer critically depends upon the details of the cure chemistry used to produce the thermoset. In order to better understand and monitor the cure chemistry, quantitative analysis of the FT-IR response has been developed for describing the epoxy-amine curing reaction as well as monitoring the hydrogen bonding that occurs in these systems The FT-IR analysis includes (i) quantitative deconvolution of complex peaks into individual spectral contributions, (ii) peak identification via DFT analysis and …

Preparation Of Mesoporous Silica Supported Ruthenium Oxides And The Application And Kinetic Study In The Catalysis Of Water Oxidation, Yang Zhang

Open Access Dissertations

Photo-induced water splitting of water into H2 and O2 has been a major focus in the development of clean and renewable energy. The development of viable and efficient catalysts that facilitates O2 production remains the major challenge in the study of the corresponding half-reaction of water oxidation. There are plenty of metal oxides reported active in the catalysis of water oxidation. However, several important performance bench marks of those materials, such as the non-stoichiometric production of O2, slow reaction rate and/or low quantum efficiency, remain to be improved.

Ruthenium oxide (RuO2) has long been known as one of the most …

Utilizing Electron Microscopy And Spectroscopy Methods To Understand Water Structure And Water Doping, Lior Miller

Open Access Dissertations

Water is the second most common element in the universe and the most studied material on earth. Most of the studies concerning water are from the fields of chemistry and biology. Hence, the structure of water molecules and short range order and interactions are well characterized and understood. However, the collective arrangement of water molecules and the long range order are still missing. Understanding of this long range order in water is needed, as it is the key to many water activities.

To fill this gap, this study utilizes a new direct method for characterization of water in the vapor …

Polysaccharide-Based Nanocarriers For Improved Drug Delivery, Nan Zhang

Dissertations - ALL

The field of drug delivery has provided a solution to the limited efficacy and high toxicity of many drugs. Nano-sized drug carriers are popular because their size allows for selective accumulation in the diseased area. Polysaccharides are non-toxic and biodegradable natural polymers that can serve as the basis for these nano-sized carriers. Polysialic acid (PSA) is such a polysaccharide with strong hydrophilicity that may reduce uptake by the reticuloendothelial system and prolong drug circulation. In this study, we developed PSA-based nanocarriers, specifically micelles and nanoparticles, for improved drug delivery with improved efficacy and minimized toxicity. PSA-based micelle systems were developed …

Synthesis Of Platinum And Platinum-Copper Branched Nanoparticles For Electrooxidation Of Methanol, Eric Courtland Taylor

Graduate Theses and Dissertations

Platinum and Pt alloys are among the most important heterogeneous catalysts for many organic reactions and electrochemical reactions associated with the fuel cell technologies. How to reduce Pt usage while maintaining the performance of the catalysts becomes a subject for intensive research in materials chemistry. For heterogeneous catalysis, the catalytic reactivity and selectivity are strongly correlated with different crystallographic facets exposed on the surface. The facets with high-index planes whose Miller indices with at one is larger than unity are generally more active than those with low-index planes (e.g., {100}, {111}, and {110}). Tuning the morphology of the nanoparticles to …

Improving The Stability Of High And Low Bandgap Polymers Organic Photovoltaic Devices Using A Solution Based Titanium Sub-Oxide Interfacial Layer, Kurniawan Foe

Electrical & Computer Engineering Theses & Dissertations

The improvement in device efficiency has brought organic photovoltaic (OPV) devices closer to commercial viability, highlighting the importance of studying the lifetime and stability of OPV devices. At present, the lifetime and stability of OPV devices is much shorter and poor mainly caused by oxygen, moisture, and light resulting in the oxidation on low work function electrodes and the degradation of the morphology of the photoactive layer. To improve the lifetime and stability of the OPV devices, we used newly developed low bandgap polymer, PCDTBT, as the electron acceptor material and a solution based titanium sub-oxide (TiOx) interfacial layer inserted …

Degradation Kinetics And Functional Design Of Linear Self-Immolative Polymers, Ryan A. Mcbride

Electronic Thesis and Dissertation Repository

Linear self-immolative polymers display a potential to address many of the limitations in the control over the degradation process in traditional biodegradable polymers. These materials are unique relative to most degradable 
polymers, in that they undergo end-to-end depolymerization in
 response to the cleavage of a stabilizing end-capping agent. Although one of their cited 
attributes is a dependence of their degradation time on chain length, no conclusive study has been conducted to demonstrate and study this 
effect. Using a previously reported linear self-immolative backbone derived from alternating 4-hydroxybenzyl alcohol and N,N’-dimethylethylenediamine spacers, this work offers the first conclusive study demonstrating …

Butyl Rubber-Aliphatic Polyester Graft Copolymers For Biomedical Applications: Synthesis And Analysis Of Chemical, Physical And Biological Properties, Bethany A. Turowec

Electronic Thesis and Dissertation Repository

Biomaterials can be used in a wide variety of medical applications owing to their breadth of characteristics that can be imparted by varying their chemical structures. Butyl rubber (IIR), which is a copolymer of isobutylene (IB) and small percentages of isoprene (IP), is particularly attractive as a biomaterial because of its elastomeric mechanical properties, biocompatibility, impermeability and high damping characteristics. IIR is typically vulcanized through chemical-based crosslinking mechanisms. However, these methods are not acceptable for biological applications. This thesis focuses on the synthesis of IIR-polyester graft copolymers by grafting biodegradable and biocompatible polyesters including poly(caprolactone) (PCL) and poly(d,l-lactide) (PDLLA) to …

Nanomaterials For Biological Applications: Drug Delivery And Bio-Sensing, Hui Ma

University of New Orleans Theses and Dissertations

The idea of utilizing nanomaterials in bio-related applications has been extensively practiced during the recent decades. Magnetic nanoparticles (MPs), especially superparamagnetic iron oxide nanoparticles have been demonstrated as promising candidates for biomedicine. A protective coating process with biocompatible materials is commonly performed on MPs to further enhance their colloidal and chemical stability in the physiological environment. Mesoporous hollow silica is another class of important nanomaterials that are extensively studied in drug delivery area for their ability to carry significant amount of guest molecules and release in a controlled manner.

In this study, different synthetic approaches that are able to produce …

Study Of Immobilizing Cadmium Selenide Quantum Dots In Selected Polymers For Application In Peroxyoxalate Chemiluminescence Flow Injection Analysis, Christopher S. Moore

Electronic Theses and Dissertations

Two batches of CdSe QDs with different sizes were synthesized for immobilizing in polyisoprene (PI), polymethylmethacrylate (PMMA), and low-density polyethylene (LDPE). The combinations of QDs and polymer substrates were evaluated for their analytical fit-for-use in applicable immunoassays. Hydrogen peroxide standards were injected into the flow injection analyzer (FIA) constructed to simulate enzyme-generated hydrogen peroxide reacting with bis-(2,4,6-trichlorophenyl) oxalate.

Linear correlations between hydrogen peroxide and chemilumenscent intensities yielded regression values greater than 0.9750 for hydrogen peroxide concentrations between 1.0 x 10^-4 M and 1.0 x 10^-1 M. The developed technique’s LOD was approximately 10 ppm. Variability of the prepared …

Strategic Electronic Property Control Of Self-Assembling Pyrazine-Acenes, Lacie Brownell

UNLV Theses, Dissertations, Professional Papers, and Capstones

Control of electronic properties in organic semiconductor materials is essential for electro-optical applications such as field-effect transistors, light-emitting diodes, and photovoltaic devices. This work is focused on two systems that highlight different approaches for the manipulation of electronic properties: (I) the development of electron-deficient (n-type) materials by selective lowering of E_LUMO and (II) low energy gap materials by controlling both E_LUMO and E_HOMO

To specifically lower E_LUMO, a pyrazine-acene π-platform was extended using electron-withdrawing moieties. These include: pyridine, pyrazine, and benzothiadiazole (system I). From the base pyrazine-acene, the most significant change in E_LUMO of …

Probing Bonding And Dynamics At Heterogeneous Adsorbate/Graphene Interfaces, Eric Charles Mattson

Theses and Dissertations

Graphene-based materials are becoming an astoundingly promising choice for many relevant technological and environmental applications. Deriving graphene from the reduction of graphene oxide (GO) is becoming a popular and inexpensive route toward the synthesis of these materials. While the desired product from GO reduction is pristine graphene, defects and residual oxygen functional groups inherited from the parent GO render reduced graphene oxide (RGO) distinct from graphene. In this work, the structure and bonding for GO and RGO is investigated to the end of a working understanding of the composition and properties of these materials. In situ selected area electron diffraction …

Functional Organic Nanomaterials, Ryan R. Kohlmeyer

Theses and Dissertations

π-Conjugated polymers have a wide range of applications such as photovoltaics, light-emitting diodes, and sensors. To gain a better understanding of these systems, monodisperse oligomers can be used as a more simplistic model to generate predictive structural and physical properties of corresponding polymers. A divergent/convergent synthetic approach to synthesis of monodisperse π-conjugated oligomers has been developed. These well-defined, thiophene-containing molecular building blocks have been successfully coupled to a ferrocene hinge, which has been found to be highly efficient in the transport of gold atoms using a gold scanning tunneling microscopy tip.

Carbon nanotubes (CNTs) represent a rare class of materials, …

New Effects Of Aging And Lattice Intercalation On Surface Properties Of Titanate Nanobelts, Roger Williams

Graduate Theses and Dissertations

Titanate nanobelts (NBs) have structural characteristics beyond that of clays. Due to a negatively charged lattice matrix of edge-shared TiO6-octahedra, the location of intercalated cations within the interlayer space may dictate the charge-conductions. This environment may in turn govern the lattice-framework's stability and surface properties, based upon our preliminary

data.

On that basis, these nanomaterials have been found in our lab to possess superb biological compatibility that is closely related to the types of the intercalated cations. In addition, a prolonged agitation was proven to enable us to manipulate the titanate NBs' length. In a parallel study, a ripening was …

Infrared Light Induced Bending Of Liquid Crystalline Elastomer Composite-Silicone Bilayer Films, Maika Moua

Theses and Dissertations

This research centers on infrared (IR) light-induced bending of liquid crystalline elastomers (LCE) composite-silicone bilayer films. Two new developments are presented in this thesis. First, the reversible infrared (IR) induced bending of 0.1% (w/w) single walled nanotube (SWNT)-LCE/silicone bilayer films were successfully prepared and used for fabrication of functioning devices such as folding, grabbing, and crawling structures. Second, the use of adding a filler (absorbs specific wavelength range), such as Dye 1002, into the LCE matrix achieved wavelength selectivity in LCE systems. The 0.2% (wt/wt) Dye 1002-LCE/silicone bilayer films demonstrated bending under a 980 nm laser source but no bending …